274 
The Collecting Arvea—It follows from the above that the collecting 
area must be in the near vicinity of the springs, and a study of the 
topography, stratigraphy and structure thereabout locates it with reason- 
able certainty. A glance at the section (Fig. 2) from Sugarloaf Mountain 
southeastward through Hot Springs Mountain will indicate the collecting 
area. The surface of the overturned, anticlinal valley between Sugar- 
lonf and North Mountains is higher than the level of emergence of the 
springs. The rocks outcropping over the area are the Bigfork chert and 
the Polk Creek shale, the former occupying most of the area. 
The considerable thickness of the Bigfork chert, its much fractured 
pature and the thin layers of which it is composed, all combine to make 
it a water-bearing formation of unusual importance. The greater num- 
ber of the fine springs in the Ouachita area between Hot Springs and the 
western border of the state come from this horizon. In many places this 
formation occurs in anticlinal valleys with its highly inclinal beds trun- 
cated, affording the most favorable condition for the intake of water. <A 
glance at figure 2 will show that these conditions obtain in the area _ be- 
tween North Mountain and Sugarloaf Mountain. In addition to the favor- 
able structure for the reception of water there is the stratigraphic condi- 
tion for its retention brought about by the overlying Polk Creek shale. As 
a consequence of the topography, structure and stratigraphy the water is 
collected in the basin shown in the map (Fig. 1), conducted through the 
Bigfork chert beneath the North Mountain syncline, and rises in the Hot 
Springs anticline, at the western end of which it emerges in the hot springs. 
including several of very weak flow, there are said to be seventy-two of 
these springs, and they are confined to a narrow strip about a quarter of a 
mile long. 
The exact location of the springs is attributable to the southwestern 
plunge of the Hot Springs anticline, and as has been stated by Mr. Walter 
Ilarvey Weed probably to fracturing and possible slight faulting in the 
process of folding, as shown in figure 3. 
While not relevant to the title of the paper, it might be added that 
the considerable number of dikes in the immediate vicinity of the hot 
springs, the large number (eighty are known) only a few miles to the 
south on and near the Ouachita River, and the areas of igneous rock at 
Potash Sulphur Spring, Magnet Cove and other places. force the sugges- 
SHUOGS Clik. 
